1. Field of the Invention
This invention relates generally to building ventilation, and more specifically to an improved method and apparatus for constructing and installing roof ventilation units for attics and other confined spaces.
2. Description of the Prior Art
It is desirable to ventilate attics and other confined spaces in a building unit to remove accumulated heat and moisture. For example, solar radiation is the principal source of heat in an unventilated attic of a home. Temperatures can reach one hundred fifty degrees Fahrenheit or more when the sun is at its zenith, even when the outside temperature is in the ninety to one hundred degree range. In cold climate areas, combinations of high humidity and low outside temperatures can cause frost to form and accumulate on the underside of roof sheathing.
As the threat of indoor air pollution becomes increasingly prevalent, more and more people are concerned about properly ventilating their homes. Unfortunately, venting a tile roof presents architects, roofers, and contractors with a serious challenge; how to properly ventilate without leakage, and without destroying the integrity of the original roof design.
Numerous mechanical devices have been designed to be installed in a roof to ventilate such an attic space. However, no known devices utilize naturally occurring convection effects and pressure differentials to ventilate a space, while still maintaining a desired aesthetic consistency with the roof covering material.
The method and apparatus for roof ventilation of this invention provides a cloaked vent tile which can be used on curved or flat tile roofs to vent attic space, space between rafters on bolted ceilings, or other difficult to vent hip or gable roofs where tile can safely be utilized. The inventive apparatus is shaped like a roof tile itself, and thus is inconspicuous and unobtrusive when installed. The inventive unit blends with the field and/or ridgeline tile, has no lead flanges to solder and will eliminate the cutting of tile for fitting, thereby enhancing the beauty of a tile roof while reducing labor costs and risk of leaks. Thexe2x80x9cinvisibilityxe2x80x9d and simple procedure of installation allows the use of any number of units to fill any requirement.
The inventive device simply takes the place of a field or ridgeline tile. Units are installed between rafters for best results. The base of the unit may be used to mark the opening, after which a hole is cut in the roof, roofing cement is applied to the base flange, and the base is nailed or otherwise secured in place. It is common roofing practice to seal around the base with plastic cement and strips of felt or fabric. Finally, the unit cover is placed over the base and the remainder of the roof tile application is completed. The unit can be installed at both the eave and ridge line to provide natural air convection, allowing the roof to breath year round, expelling damaging hot air and moisture laden air.
The inventive apparatus utilizes standard size vent openings (e.g., 25, 50 or 100 square inch screened openings) installed on the roof surface. The vent base and cap are preferably made of galvanized sheet metal (e.g., 26 gauge galvanized steel with #10 mesh galvanized wire insect screen) or copper (e.g., 16 ounce copper sheet with #10 mesh copper screen). The vent caps may be painted or otherwise fused with color to match the surrounding (standard) tiles.
Convection is one of the ways an attic can breath. This occurs when the air temperature in the attic and the outside air temperature differ, and the elevations of the ventilation openings are at their furthest extremes. As hot air escapes through the ridge of the roof, cooler air enters through the vents along the cornice. This phenomenon occurs even at zero windspeed. Another form of ventilation is air pressure caused by wind. Wind moving over an attic will generate a vacuum in the attic which is the result of negative air pressure on the windward side and positive pressure on the downwind side (check). Air is pulled and pushed through the vents as a result of these pressures allowing the attic toxe2x80x9cbreathxe2x80x9d.
When placed strategically on the roof where venting is most important, the inventive vent tiles provide uniform, constant air movement via natural air convection. The result is safe, lead-free, leak proof ventilation.
The vent tiles of this invention are easy to install and functional in design. They blend so unobtrusively with the building, preserving the beauty of the original design. The tiles will not present a fire hazard, and can be used on both new and restored buildings. The cost is comparable with standard ventilation systems, yet they are cheaper to install.